fetchDebianPatch: init

pkgs/build-support/fetchdebianpatch/default.nix

@@ -0,0 +1,13 @@
+{ lib, fetchpatch }:
+
+lib.makeOverridable (
+  { pname, version, debianRevision ? null, name, hash, area ? "main" }:
+  let versionString =
+    if debianRevision == null then version else "${version}-${debianRevision}";
+  in fetchpatch {
+    url =
+      "https://sources.debian.org/data/${area}/${builtins.substring 0 1 pname}/"
+      + "${pname}/${versionString}/debian/patches/${name}.patch";
+    inherit hash;
+  }
+)

pkgs/top-level/all-packages.nix

@@ -1173,6 +1173,8 @@ with pkgs;
       tests = pkgs.tests.fetchzip;
     };
 
+  fetchDebianPatch = callPackage ../build-support/fetchdebianpatch { };
+
   fetchCrate = callPackage ../build-support/rust/fetchcrate.nix { };
 
   fetchFromGitea = callPackage ../build-support/fetchgitea { };